So Spring uses Jackson and the Jackson library is composed of three components: Jackson Databind, Core, and Annotation. I did not add anything specific to my maven pom.xml for Jackson so the dependency got inherited somewhere. So after some Google jobs I figured out the spring-boot-starter-parent uses some older FasterXML/Jackson libs which seem to screw things up.

I ran into this as well, with the same solution, except I’m bumping up against it again when deploying to Docker using on a maven:3.5.3-jdk-8-alpine prototype. I haven’t solved it yet, but I bet there’s yet another Jackson-core being pulled in with Tomcat or the image’s Maven installation.